1. Field of the Invention
The present invention relates to an image forming optical system and an electronic image pickup apparatus using the same.
2. Description of the Related Art
As a zoom lens system for an image pickup apparatus with a high zooming ratio in which, an image pickup element of a large number of pixels is used, a zoom lens system disclosed in Japanese Patent Application Laid-open Publication No. 2007-226142 is available. This zoom lens system includes a first lens unit, a second lens unit, and a third lens unit. Here, the third lens unit includes a cemented lens. Moreover, this cemented lens has a sandwich structure in which, a resin having a specific partial dispersion ratio and Abbe's number is sandwiched.